Wear Measurement and Assessment of Explanted Cross-Linked PE Acetabular Cups Using a CMM

Wear has been considered the main limiting factor in the longevity of hip replacements. Wear analysis is thus essential for determining wear-related failure mechanisms and prediction of wear, which will consequently enable biomedical engineers to improve the design, material, and service life of the bearing components. This article presents wear measurement and assessment of the explanted conventional cross-linked polyethylene (XPE) and second-generation highly cross-linked polyethylene cups (X3) using a coordinate measuring machine (CMM). An expanded uncertainty analysis was performed to assess the performance of wear measurement. Wear measurement using the CMM method was validated with the gravimetric technique. The normalized error between volumetric wear measurement of the CMM method and that of the gravimetric technique was estimated to be always less than 1, suggesting that the CMM method applied to explanted hip wear measurements under the specific conditions was accurate and reliable. The approach to CMM measurement with uncertainty analysis was shown not only to locate 3D wear scar and wear direction but also to accurately quantify linear and volumetric wear with a maximum volumetric uncertainty of ±3.15 mm³ (95% confidence level). It is shown that identifying the key uncertainty components involved in the measurement process including validation, which contributes to an overall expanded uncertainty budget, is crucial to improve the confidence and the reliability of hip wear measurement results using a CMM.     

Optical disc jitter generator and its calibration system

Jitter is one of the most important parameters for optical disc evaluation. This paper presents a design of a simulated optical disc jitter generator based on a sinusoidal frequency-modulated (FM) signal. An innovative method is proposed to calibrate the jitter generator based on the Bessel-zero method. Finally, measurement uncertainty of the calibration system is described. The results of theoretical analysis and experiments indicate that the expanded uncertainty of measurement is 0.13% in CD mode, and 0.18% in DVD mode, k = 2.     

Critical aspects of the uncertainty budget in the gravimetric PM measurements

The interest in particulate matter (PM) exposure studies leaded the regulatory authorities and the air quality management community in updating new air quality standards. In order to characterize the current exposure experienced by people, measurement should be carried out also taking into account periodic PM concentration fluctuations. For this purpose continuous or semi-continuous measurement techniques were developed even if the reference method used to measure the air quality standards is still based on the gravimetric analysis of particle collected through filtration technique over a period of 24 h.In this work the authors carried out a metrological characterization of the gravimetric method in measuring PM concentrations. The critical aspects of the technical standard in evaluating the uncertainty budget of PM measurement are stressed and the influence of single uncertainty contributions to the combined uncertainty is also shown. Finally, a comparison between European and US standards in PM measurement is made.     

基于测量数据不确定性的结构参数识别

基于模糊理论提出了考虑测量数据不确定性的结构物理参数识别方法。首先,对不确定性参数的有限个离散测量数据进行初步筛选,利用数据拟合方法建立隶属度函数;其次,通过截集法对不确定性参数进行区间分析,得到不确定性参数的区间估计;最后,利用矩阵特征值反问题方法识别结构的刚度矩阵。算例分析表明,该方法在考虑测试数据不确定性的基础上能较好地识别结构刚度,并给出结构刚度区间,使得分析结果更符合实际工程情况。     

运用改进的教学-模拟退火算法辨识关节臂式三坐标测量机的结构参数

为了提高关节臂式三坐标测量机的精度，降低其运动不确定度，提出了一种改进的教学-模拟退火混合优化算法来辨识其结构参数并补偿其误差，从而提高其精度。分析了教学算法(teaching-learning-based optimization, TLBO)的优缺点并对其进行改进从而得到改进的教学算法；提出了一种收敛精度转换准则，将改进的教学算法(modified TLBO, mTLBO)和模拟退火算法(simulated annealing, SA)融合得到改进的教学-模拟退火算法(mTLBO-SA);基于此理论和单点重复率误差实验，分别用TLBO、SA和mTLBO-SA对关节臂式三坐标测量机的结构参数进行了辨识；分别用辨识前后的关节臂式三坐标测量机再次进行单点重复率误差实验，并比较相应的实验结果。实验结果表明，所提算法能有效且高效地辨识关节臂式三坐标测量机的结构参数，进而有效提高其定位精度，降低其运动不确定度。     

重力式自动装料衡器的测量不确定度分级评定

本文结合检定工作中的实际案例,用不同检定法对重力式自动装料衡器的测量不确定度进行分级评定.     

三坐标机测量齿轮齿廓的不确定度评价

介绍了坐标测量中几种常用的不确定度评价方法.指出传统的三坐标测量机的测量不确定度评价方法大都不适用于评价坐标测量中面向对象的测量不确定度,并对使用蒙特卡洛方法评价测量不确定度进行了研究.首先,根据三坐标测量机详细标定文件及补偿策略说明建立测量模型.然后,将测量中的采样点通过测量模型生成大量测量结果,并以此评价测量不确定度.在齿廓评价实验中,评定齿廓误差的测量不确定度为0.96 μm时,多次评价结果之间的最大差值不超过0.03 μm,具有可靠的理论依据和较稳定的评定结果.文章指出,目前商用三坐标测量机大都不能为特定的测量对象提供测量不确定度报告,使用蒙特卡洛方法有希望改变此现状.     

Blow-down calibration of a large ultrasonic flow meter

Oil and gas production industries use large (diameter > 0.8 m) ultrasonic flow meters (USMs) to measure exhaust gas from flare stacks, emissions from smokestacks, flow of natural gas, etc. Since most flow laboratories do not have compressors with sufficient flow capacity (>10 kg/s) to calibrate large flow meters, calibrations are performed using the blow-down method where flow is generated by discharging high pressure tanks, leading to significant flow transients. We used an array of critical flow venturis (CFVs) in a blow-down facility to calibrate a large (D = 89.5 cm) 8-path ultrasonic flow meter. The flow transients associated with the blow-down process caused large spatial and temporal variations in temperature that dominated (40%–67%) the uncertainty budget. Our uncertainty analysis accounts for transient-generated uncertainties and provides guidelines for improving blow-down calibrations of large flow meters.     

Estimation of uncertainty of mean velocity of flue gas in a conduit as determined by the traverse method within the gravimetric measurement of particulate concentration

In gravimetric measurements of dust emissions from industrial technological plants, the required mean gas velocity in a conduit is often determined by Pitot traverse method. It is commonly seen as a method giving good approximate values of mean gas velocity, although the actual rate of this approximation is not considered in the analysis of measurement results. It was seen that there was a need to establish what magnitude of error might occur in practice due to the small number of measurement points and typical non-uniformity of the gas velocity profiles in conduits of rectangular cross-section. The calculations were based on the concept of treating a measurement plane as one consisting of a set of elementary planes. The elementary gas velocity profiles in these elementary planes were simulated, the mean velocity for these profiles were calculated based on point velocity values, and the measurement uncertainty of this mean velocity determined. This uncertainty results in the uncertainty of the mean velocity across the entire measurement plane. It appears that, depending on the number of measurement points and gas velocity profile non-uniformity, the value is not small and is of the order of several percent, and hence needs to be taken into account in the budget of the combined uncertainty of mean velocity, which in turn contributes to the uncertainty of gas volumetric flow rate and dust pollutant mass flow rate.     

BL9冷爆口机玻璃器皿设备的绿色设计

当前玻璃器皿加工设备的设计大多还局限于传统设计，产品开发过程中很少考虑其环境属性和人的劳动强度。这里对以BL9冷爆口机为例讲述在玻璃器皿制造和使用过程中对环境的影响，分析了玻璃器皿加工设备的特点，讨论了玻璃器皿加工设备设计方法现状，将绿色设计方法应用于玻璃器皿加工设备，重点研究了玻璃器皿加工设备绿色设计的三个关键技术一面向环境的设计技术、面向能源的设计技术和人机工程设计技术。     

基于山西吹制玻璃器皿产业引入绿色设计理念

发展循环经济已经成为目前我国经济发展的趋势。作为山西主要出口外贸增长点的吹制玻璃器皿行业来说,是一个传统的高污染、高能耗行业。引入绿色设计的理念,无论在初期的设计工艺还是后续的生产决策中,都为山西吹制玻璃器皿行业的发展带来了长远的利益。     

Stylus-laser surface calibration system

A stylus-laser surface calibration system was developed to calibrate the NIST sinusoidal roughness Standard Reference Materials (SRM) 2071-2075. Step height standards are used to calibrate the stylus instrument in the vertical direction, and a laser interferometer is mounted on the traversing unit of the stylus instrument to calibrate the instrument in the horizontal direction. The calibration uncertainty (±2δ) for SRM 2075 is ±1.2% for roughness calibrations ((R_a = 1 μm), and ±0.06% for spatial wavelength calibrations (S_m = 800 μm).     

Hard pressed [glass pressing]

Pressing itself was the first step to automation in the glass industry, but the job of automatically transferring a quantity of molten glass from the furnace to the moulds on an automatic press proved an obstacle to the complete mechanisation of the pressing process. it was not until 1915 that an automatic device for feeding a gob of glass to a mould on an automatic press was perfected in the USA. Fully automatic production of pressed glassware became feasible. The author gives an updated outline of the automatic production of pressed glassware     

The primary dynamic gravimetric system for gas mass flow measurement

High accuracy mass flow measurement is an enabling technology at the base of many industries. HORIBA STEC Co., Ltd. developed its own primary gas mass flow measurement system. We employed the dynamic gravimetric method in a vacuum chamber, and we use only mass and time information for mass flow rate calculation, with no correction for temperature, pressure and humidity. The system achieved 0.036% uncertainty as lowest of results with satisfactory performance of proficiency testing with NIST (National Institute of Standards and Technology). Then the laboratory has been granted ISO/IEC 17025 accreditation since 2017. This paper describes the system details and uncertainty analysis.     

CAWS600型自动气象站湿度传感器检定的不确定度分析

自动气象站各要素传感器随着时间的推移和环境的变化,测量误差将会发生漂移。为确保各要素观测数据的准确、可靠并具有可比性,定期开展自动气象站各要素的检定和校准是非常重要的。通过检定将各要素系统误差控制在允许范围内,并对检定结果进行不确定度分析,是考察检定结果可信程度的重要步骤。文章依据自动气象站检定规程要求,并根据检定数据,对自动气象站的湿度传感器检定进行不确定度分析,对自动气象站检定可信度评估具有指导意义。     

基于Pro/E的玻璃器皿压机夹模机构参数化设计

夹模机构是压机中的关键部件,对保证玻璃器皿成型质量具有重要的作用。首先介绍了夹模机构的工作原理,并对其进行了受力分析,在此基础上,详细阐述了采用虚拟样机技术,在Pro/E平台下,利用自底向上的建模方法建立了夹模机构的参数化模型库,以Access 2003作为后台数据库,以Pro/TOOLKIT及VC++6.0作为开发工具对玻璃器皿压机的夹模机构进行参数化设计的过程,最后给出实例演示,验证了该方法的可行性,通过参数化方法,提高压机夹模机构的设计效率及质量。     

一种基于棋盘格的高精度分区域相机标定方法

在视觉测量系统中,相机的标定精度至关重要,将影响整个测量系统的精度。针对现有相机标定方法难以兼顾精度和操作复杂度的问题,本文提出了一种基于棋盘格的高精度分区域相机标定方法。首先,将棋盘格置于不同位置,提取不同位置角点的世界坐标和像素坐标,对所有角点用线性变换和非线性最优算法求解出全局标定参数。然后,将角点分为中间区域角点和边缘区域角点,对两区域角点分别标定得到两组分区域标定参数。标定实验结果表明：与全局标定法相比,分区域标定法的图像平均投影误差至少降低16%。该方法操作简单,精度高,可以很好的应用于工业视觉检测。     

Uncertainty analysis of positional deviations of CNC machine tools

The assessment of the measurement uncertainty is an indispensable task in all calibration procedures. By international accord, the evaluation is to be done in accordance with the ISO Guide to the Expression of Uncertainty in Measurement (GUM). To calibrate the positional deviations of computer numerically controlled (CNC) machine tools, calibration laboratories will usually follow the guidelines in ISO 230-2 International Standard. However, that standard does not address uncertainty. In this paper, we present an uncertainty evaluation scheme that is firmly grounded in the GUM, and can therefore be of use as a guide to develop appropriate uncertainty calculations in this and similar types of calibrations.     

复杂铸件的三维测量

针对复杂铸件尺寸大,结构复杂,槽、腔多,测量时需兼顾测量效率和槽腔可测性的特点,提出了一种大视场双目光栅测量子系统和小视场光栅测量子系统相结合的立体视觉测量方法。该方法使用前者测量复杂铸件的外部可测部分;使用后者测量复杂铸件的槽腔等被遮挡部分。建立了两个测量子系统的数据拼接模型,给出了数据拼接模型参数的定标方法。最后,通过实验验证了该方法的可行性。实验结果表明：该系统测量数据拼接的均方根误差（RMSE）为0.22 mm,满足复杂铸件测量的精度要求。相比传统测量方法,该方法兼顾了测量复杂铸件速度快和可以灵活测量槽腔等被遮挡部分的特点,对工程应用具有实际指导意义。